CIS679: DiffServ Model r Review of Last Lecture r 2-bit DiffServ architecture

Review of Last Lecture r Two Planes r IntServ r DiffServ m Two types of services: relative and absolute m Basic mechanism: edge-router, core-router, PHB

2-bit differentiated service r Premium service: (type P) m admitted based on peak rate m conservative, virtual wire services m unused premium goes to best effort r Assured service: (type A) m based on expected capacity usage profiles m traffic unlikely to be dropped if user maintains profile. Out-of-profile traffic marked

Traffic Flows first hop router internal router border router host border router ISP Company A Unmarked packet flow Packets in premium and Assured flows have bit set Leaf Router Marking at Leaf Router Forwarding Metering at Border Router

Leaf router input functionality Clear A & P bits Packet classifier Marker 1 Marker N Forwarding engine Arriving packet Best effort Flow 1 Flow N Markers: service class, rate, permissible burst size

Marker function in routers r Leaf routers have traffic profiles - they classify packets based on packet header r If no profile present, pass as best effort r If profile is for A: m mark in-profile packets with A, forward others unmarked r If profile is for P: m delay out-of -profile packets to shape into profile

Markers to implement two different services Wait for token Set P bit Packet input Packet output Test if token Set A bit token No token Packet input Packet output Drop on overflow

Output forwarding r 2 queues: P packets on higher priority queue r Lower priority queue implements RED “In or Out” scheme (RIO) r At border routers profile meters test marked flows: m drop P packets out of profile m unmark A packets

Router output interface for two-bit architecture P-bit set? If A-bit set incr A_cnt High-priority Q Low-priority Q If A-bit set decr A_cnt RIO queue management Packets out yes no

RED with In or Out (RIO) r Precursor to Assured Forwarding (AF) PHB r Similar to RED, but with two separate probability curves r Has two classes, “In” and “Out” (of profile) r “Out” class has lower Minthresh, so packets are dropped from this class first r As avg queue length increases, “in” packets are dropped

RIO drop probabilities MaxP 1.0 Min out Min in Max in Max out P(drop) AvgLen More drop probability curves (WRED)?

Border router input interface Profile Meters Arriving packet Is packet marked? Token available? Token available? Clear A-bit Drop packet Forwarding engine A set P set token Not marked no

Conclusion r An example of relative DiffServ m 2 bit architecture Premium service, Assured service m Marker at leaf router m Output forwarding m Meter at border router

Final Review on Part 1 r Multimedia basics m The four major steps m Compression techniques Redundancy Classification m JPEG DCT m MPEG Motion prediction I, B and P frames, GOP Different units

Final Review on Part 2 r Better then best effort services m Multimedia requirements to networks m TCP Window control, Reliability, Flow and congestion control m UDP Why UDP for multimedia? TCP friendly CUDP etc. m Buffer management Drop-tail, RED and its variations m HTTP and RTP m Multicast: address, routing, transport layer and QoS m Anycast: network-layer and application layer anycast

Final Review on Part 3 r Beyond the best effort services m Four Principles m Policing m Scheduling Its relationship with buffer management m RSVP Receiver driven and soft-state m Integrated Service model m Differentiated Service model